Figure 6B shows that infection of NIH 3T3 cells with titer-matched MSCV-BCR/ABL-GFP-IRES-N17H-Ras and MSCV-BCR/ABL-GFP-IRES-Neo retroviruses yielded similar levels of BCR/ABL-GFP expression, as shown by western blotting using an anti-Abl antibody. Here, ABL1 is linked to infection.